Reduction of adhesions using controlled delivery of active oxygen inhibitors

ABSTRACT

SOD and other active oxygen inhibitors are directly applied in combination with a barrier material at local sites of tissue injury to prevent or decrease formation of adhesions and undesirable proliferation of cells. Preferred barrier materials are polymeric hydrogels providing controlled release of AOI which are directly applied to the afflicted tissue. Examples demonstrate the effects of SOD on pelvic adhesions in the rat when administered by intraperitoneal (I.P.) bolus and by localized sustained release from a topically applied hydrogel system.

This application is a continuation of Ser. No. 08/689,139, filed Jul.29, 1996, now U.S. Pat. No. 5,785,993, which is a continuation of Ser.No. 08/410,219, filed Mar. 24, 1995, now abandoned.

BACKGROUND OF THE INVENTION

The present invention is generally in the area of prevention of surgicaladhesion.

Adhesions are a common complication of surgery. They may develop in avariety of areas in the body, and are characterized in that tissueswhich were separate before surgery become bonded together in the processof healing. The type and degree of damage caused by adhesions isvariable, ranging from life-threatening, as in the intestines due toblockage, to extremely disabling, as in tendons or spinal cord, tochronic pain and infertility in the pelvic cavity, to being obstructiveof further surgery in the pericardium. Postoperative formation of pelvicadhesions remains a serious problem in patients undergoing gynecologicalsurgery and is a principal cause of infertility. In general, the mostcommon causes of pelvic adhesions in women are prior surgery,endometriosis and pelvic inflammatory disease.

Injury to intact peritoneum as a result of surgical insult or infectionbegins a cascade of pathophysiological events. Within three hours ofsurgical insult or infection, there is damage to vasculature, resultingin increased vessel permeability, and an inflammatory response,resulting in further vascular damage due to ischemia and reperfusioninjury. The exudate of serosanguionous fluid and fibrin matrix leads tofurther ischemia, resulting in persistence of fibrin matrix andcollagenous adhesions, as well as fibrinolysis to yield fibrin splitproducts, absorption of fibrin matrix, and normal repairs. This cascadeincludes the expected events associated with inflammation including bothneutrophil and macrophage migration to the site of inflammation.Associated with this cell migration is a rapid respiratory burst leadingto the generation of oxygen radicals at the site of inflammation. In theabsence of sufficient free radical scavengers, high concentrations ofoxygen radicals are capable of damaging the surrounding intact cells,including those responsible for vascular integrity. This increasedpermeability of blood vessels can lead to exudation of proteinaceousserosanguinous fluid which serves as a matrix for fibrinous adhesions.In addition, increased vascular permeability leads to local interruptionof blood flow and eventual cell death in the vessels comprising thevascular supply. Reperfusion of tissues, following this ischemic event,leads to further generation of oxygen radicals and, ultimately, furtherexacerbates the degree of fibrinous adhesion formation.

Under normal circumstances, the fibrinolytic capacity of plasminogenactivator activity (PAA) leads to the absorption of such fibrinousdeposits and to conventional peritoneal healing. However, in thepresence of severe tissue injury (e.g. following surgical trauma), adecrease in PAA leads to abnormally persistent fibrin deposits and,ultimately, mature collagenous adhesions. Meticulous dissection (i.e.adhesiolysis) continues to be the most widely accepted treatment forexisting adhesions. A substantial fraction of surgery therefore requiresfollow-up surgery to repair the effects of the adhesions. This procedureis generally called “adhesiolysis”; in some organ systems, the procedurehas specific names, such as “tenolysis” in the freeing of tendons.

The list of potential therapeutic modalities used in prevention offormation and reformation of adhesions is extensive and includesinfusion of liquids into the pelvic cavity at the time of surgery,mechanical barriers between two opposing surfaces, and intravenouslyinjected or topically applied pharmacologic agents (Tulandi, “Effects ofRinger's Lactate on Postsurgical Adhesion. In: Diamon, et al., eds, vol.381, Progress in Clinical and Biological Research (NY, Wiley-Liss 1993)59-63; Schwartz, et al., Sem. in Repro. Endocrin. 9:89-99 (1991);Pjilman, et al., Eur. J. Ost & Gyn. Repro. Biol. 53:155-163 (1994); andMonk, et al., Am. J. Obstet. Gynecol. 170:1396-1403 (1994). However, theincidence of symptomatic adhesion formation remains high, and theclinical need for adhesion prevention still exists.

Therapies of various sorts have been used to prevent the initialformation of adhesions (“primary” adhesions). These include lavage withwater-soluble polymers and/or biologically active molecules (“drugs”),which are usually not very effective. However, the use of superoxidedismutate (SOD) combined with catalase prevented or diminishedendometriosis-induced adhesions in rabbits in a study by Poretz et al,(Int. J. Fertil. 36:39-42, 1991). Permanent mechanical barriers, such asTeflon™ sheets, can be effective but are difficult to remove; anddegradable barriers such as oxidized cellulose (InterCeed™, Johnson &Johnson) and degradable polymeric gels (Sawhney et al, 1993; Hill-Westet al 1994) can have significant utility in the prevention of primaryadhesions. Tsimoyiannis et al (Acta Chir. Scand. 155: 171-174, 1989)reported reductions of about 50% in the incidence and 50-70% in theseverity of ischemia-related induction of primary adhesions in rats,after administration of SOD, catalase, DMSO (dimethylsulfoxide) orallopurinol as an intravenous bolus before surgery.

It has been hypothesized that the commonality of these drugs is in theirinhibition of the pathway leading to oxidative damage to tissue. SOD,catalase and DMSO each directly destroy active oxygen species, such assuperoxide, peroxide, or hydroxyl radical; allopurinol is known toinhibit the enzyme xanthine oxidase, which produces hydrogen peroxide.These compounds which directly or indirectly inhibit the effect ofactive oxygen species on tissue are referred to herein as “active oxygeninhibitors”, or AOIs. Superoxide dismutase (SOD, dimer MW=31.5 kDa,tetramer=67 kDa) has been efficacious in the treatment ofischemic/reperfusion events in a wide variety of tissues includingbrain, kidney, and heart (Schneider, et al., Fr. Rad. Biol. & Med.3:21-26 (1987); Zimmerman, et al., Am. J. Med. Sci. 307:284-292 (1994);Voogd, et al., Fr. Rad. Biol. & Med. 11:71-75 (1991); Fridovich, Arch.Bioch. & Biophys. 247:1-11 (1986); Kontos, et al. CNS Trauma 3:257-263(1986)). There is also evidence that SOD can be effective in theprevention of pelvic adhesions (Tsimoyiannis, et al., Acta Chir. Scand.155:171-174 (1989); Portz, et al., Int. J. Fert. 36:39-42 (1991);O'Leary, et al., Ann. Surg. June:693-698 (1987)). However, efficacyusing SOD has been limited, due to its rapid elimination from thebloodstream (Petkau, et al., Res. Commun. Chem. Pathol. Pharmacol.15:641-654 (1976); Odlund, et al., Pharmacol. Toxic 62:95-100 (1988)).Improved efficacy has resulted from strategies for increasing SODcontent in the bloodstream including chemical modification to reduce therate of elimination (Pyatak, eta l., Res. Comm. Chem. Path. Pharm.29:113-127 (1980); Hill-West, et al. Obstet. Gynecol. 83:59-64 (1994))and frequently repeated injections (O'Leary, et al., 1987).

Removal of adhesions once formed is substantially more difficult thanprevention of adhesion formation. Unfortunately, formulations whicheffectively prevent primary adhesions (e.g., Hill-West et al, 1994) canbe substantially less effective in preventing re-adhesion afteradhesiolysis (“secondary” adhesions). While the exact biologicaldifferences between primary and secondary adhesions are not known, it ispossible that the formation of primary adhesions depends on thepersistence of fibrin bridges between the disjoint parts, which aresubsequently colonized by other cells and develop into permanentvascularized tissue. Anything disrupting formation or stabilization ofthe initial fibrin bridge would tend to prevent primary adhesionformation. Secondary ahesions, however, maybe the result of the normalhealing process applied to injured pre-existing tissue, i.e. the lysedprimary adhesion. The healing process, while not yet understood indetail, involves the mobilization of several cell types and theformation of new collagen, and typically has initial stages lasting forup to two weeks followed by several months of maturation to obtain fullrepair. Because of these differences, it is possible that treatmentseffective in primary adhesion prevention will require enhancement toprevent reformation of adhesions after adhesiolysis.

In summary, there have been no reports of compositions totally effectivein eliminating adhesions, especially in patients in which the injury isrepeated, as in the case of patients having had multiple surgeries.

It is therefore an object of the present invention to provide a methodand compositions for preventing adhesions following surgery orinfection.

SUMMARY OF THE INVENTION

SOD and other active oxygen inhibitors are directly applied incombination with a barrier material at local sites of tissue injury toprevent or decrease formation of adhesions and undesirable proliferationof cells. Preferred barrier materials are polymeric hydrogels providingcontrolled release of AOI which are directly applied to the afflictedtissue.

Examples demonstrate the effects of SOD on pelvic adhesions in the ratwhen administered by intraperitoneal (I.P.) bolus and by localizedsustained release from a topically applied hydrogel system.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a bar graph of the percent efficacy in primary adhesions ratuterine horn model of treatment with hydrogel (∥ ∥ ∥), SOD alone (≡),and SOD locally delivered via the hydrogel (open bar), as compared withuntreated animals (/ / /) at dosages of 2000 U SOD/ml versus 10,000 USOD/ml.

FIG. 2 is a bar graph of the percent efficacy in secondary adhesions ratuterine horn model of treatment with hydrogel (∥ ∥ ∥), SOD alone (≡),and SOD locally delivered via the hydrogel (open bar), as compared withuntreated animals (/ / /) at dosages of 2000 U SOD/ml, 5,000 U SOD/mland 10,000 U SOD/ml.

FIG. 3 is a bar graph of the percent efficacy of hydrogel (∥ ∥ ∥), SODalone and SOD locally delivered via the hydrogel compared with untreatedanimals (solid bar), for both primary (open bars) and secondary adhesionmodels.

DETAILED DESCRIPTION OF THE INVENTION

As described herein, a method and compositions providing for preventionor minimization of tissue adhesions, especially secondary tissueadhesions, is described where active oxygen inhibitors such as SOD arelocally applied to the injured area in a hydrogel formulation. In thepreferred embodiment, the hydrogel is polymerized in situ byphotopolymerization of a biocompatible, biodegradable macromer solutionsuch as a polyethylene glycol dilactide diacrylate. Alternatively, or inaddition, a barrier material can be used in combination with the activeoxygen inhibitor, as well as controlled release means for the activeoxygen inhibitor (“AOI”). These materials, including the hydrogels, aregenerally referred to as “barrier materials” unless otherwise specified.

Barrier Materials:

Primary Barrier Materials:

Barrier materials can be administered as fluids, pastes, or other fluentforms, and locally altered in the body to form conforming barriers at ornear the site of application, or as solid barriers. The barriermaterials should be-biologically benign, and in particular, should notinduce a severe local inflammatory response. Essentially all implantscause a transient local reaction after implantation. A benign, orbiocompatible, material does not provoke a prolonged or escalatinginflammatory response. Preferred barrier materials should be degradableor should dissipate within a reasonable time by exposure to natural bodyfluids. Preferred barrier materials should also serve as a depot forcontrolled release of AOIs over a period of hours to weeks, to allowlocal delivery directly to injured tissues.

A preferred barrier material is a gel, most preferably a gel materialwhich is absorbed in vivo, whether by gradual dissipation into solution,spontaneous hydrolysis, enzymatic degradation, or a combination ofthese. Examples of suitable gels are the Pluronic® poloxamer gel systemsare polyalkylene oxides, some members of which form gels at bodytemperature but are liquid at room temperature; and thephotopolymerizable gels described by Hubbell et al (WO 93/17669) andSawhney et al, J. Biomed. Mats. Res. 28, 831-838 (1994). Pluronic gelsystems are known as anti-adhesion barriers (U.S. Pat. Nos. 4,911,926and 5,135,751 to Henry et al; U.S. Pat. No. 5,366,735 to Henry) and asdrug delivery vehicles (U.S. Pat. No. 5,292,516 to Viegas et al), as arethe cited Hubbell materials.

Numerous other formulations are potentially capable of serving asbarriers with drug delivery capability. These include the polymers ofU.S. Pat. No. 4,938,763 to Dunn et al, U.S. Pat. No. 5,108,755 toDaniels et al, U.S. Pat. No. 4,913,903 to Sudmann et al, U.S. Pat. Nos.5,100,992 and 4,826,945 to Cohn et al, U.S. Pat. No. 5,219,564 toZalipsky et al, U.S. Pat. Nos. 4,741,872 and 5,160,745 to De Luca et al,U.S. Pat. Nos. 4,526,938 and 4,942,035 to Churchill et al, U.S. Pat. No.4,888,413 to Domb, U.S. Pat. No. 4,511,478 to Nowinski et al, U.S. Pat.No. 4,957,744 to della Vallee et al, U.S. Pat. No. 4,925,677 to Feigen,U.S. Pat. No. 4,994,277 to Hingham et al, U.S. Pat. No. 5,364,622 toFranz et al and U.S. Pat. No. 4,804,691 to English et al. Hyaluronicacid materials, including hyaluronic acid gels and membranes, are alsosuitable for local delivery of AOIs to injured tissue.

Oxidized cellulose, administered as a fabric, forms a gel in bodilyfluids and can deliver drugs (U.S. Pat. No. 4,889,722 to Sheffield etal). However, it is believed to be somewhat inflammatory and istherefore not preferred. Purely mechanical barriers, such as “Teflon®”,fluoropolymer sheets and other non-degradable materials, are lessdesirable, but may be suitable if combined with other means forcontrolled local release of the drug directly to the injured tissue.

Although less preferred, gel barriers which are not readily degradablecan be used. These include materials such as agarose, crosslinkedpolyacrylamide, gelled polyvinyl alcohol, gelled or crosslinked HEMA(poly hydroxymethyl acrylate), crosslinked dextran, and other knowngelling materials. These can be very biocompatible, and are suitable fordrug delivery.

The concentration of the gel-forming polymer in a hydrogel is variable,as is well-known. Suitable concentrations of polymer are those whichgive a gel which has adequate mechanical properties to persist at thesite of application for at least the desired period of treatment, whichwill typically be days to weeks. Minimum effective gellingconcentrations of various polymers range from as low as 0.1% (w/w) forultrapure agarose, to between 3 and 5% for the polymers of Hubbell etal, to over 10% for some poloxamers such as Pluronics®-. Upper limitsare imposed by solubility, by viscosity, by the onset of brittleness ofthe gel, by excessive swelling after formation, by osmotic effects ofthe applied monomers on tissue, and by a desire to minimize the amountof polymer applied in a treatment. These factors and their manipulationare known in the art, and vary with the polymer. Upper concentrationlimits may vary from as low as 2% for agarose, to between 25 and 30% forthe polymers of Hubbell, to 50% or more for poloxamers.

Preferred materials for barriers and delivery means are characterized bycertain critical characteristics, including: biocompatibility; deliverytimes extending from a day up to weeks; compatibility with the AOI to bedelivered; and, in more preferred embodiments, biodegradability.Preferred materials contain at least some water, further containingphysiologically-acceptable salts and buffers; higher levels of water arepreferred, where otherwise compatible with mechanical and diffusionalproperties of the materials. It is preferred to combine the barrierfunction with the controlled-release function in a single material; ofsuch materials, hydrogels are preferred.

As shown in the Examples below, a preferred mode is the incorporation ofan AOI, preferably SOD, in a solution also containing a biocompatible,biodegradable, gel-forming photopolymerizable monomer, and suitablephotoinitiators, buffers and stabilizers; delivery of the combinedsolution to a site where adhesiolysis has been performed, and coveringthe affected areas; and photopolymerizing the composition to create abarrier gel which slowly releases the AOI during a period of days toover a week.

As noted above, the concentration of the polymerizable material isvariable. For the particular material used in the examples, thepreferred concentration of the monomer is in the range of 10% to about25% w/w in buffered isotonic saline solution. Higher concentrations tendto give slower and more prolonged release of the AOI, and to last longeras barriers, but are correspondingly more viscous, which can makeapplication more difficult if done through a laparoscope or catheter.Other materials will have different preferred concentrations, aspreviously noted.

Drug Delivery Means.

Controlled delivery means can be employed in addition to a gel, or inplace of a gel. There are a large number of physiologically-acceptabledrug delivery materials known in the art which have the followingproperties:

1. The delivery means must be localizable, or at least potentiallylocalizable, to allow the delivery of the contents primarily to aparticular target organ or region. A suitable means, although notpreferable for human use, is an osmotic pump, such as an Alzet® pump(Alza Co.)

2. The delivery means must be biocompatible, and in particular shouldnot be substantially inflammatory in the body. Illustrative controlleddelivery means include small particles of drug entrapped in abioerodible polymer such as polyglycolide, polylactide or polyanhydride,for example, U.S. Pat. No. 4,898,734 to Mathiowitz et al; U.S. Pat. No.5,175,235 to Domb; U.S. Pat. No. 5,286,763 to Gerhart et al; and U.S.Pat. No. 4,745,161 to Saudek et al, optionally coated with arelease-retarding shell, which are in turn delivered to the site atwhich adhesions are to be prevented, preferably with additional means toretain them near the site, such as a barrier membrane or a gel.Controlled delivery means are especially important when the drug to bedelivered has a high aqueous solubility and a low molecular weight.

3. Preferably, the delivery means will degrade in the body, concurrentlywith delivery of drugs or subsequently. Most of the polymers noted aspotential hydrogel materials above are biodegradable, as are thepolymers listed in the previous paragraph. Classical erodible polymers,such as poly(hydroxyacids) (e.g., polyglycolide, polylactide, andpolycaprolactone) are suitable in many situations, although they aresomewhat more inflammatory than some newer polymers.

Pharmaceutically Active Compounds

Active Oxygen Inhibitors.

As used herein, AOIs are defined as compounds which destroy, or preventthe formation of, active oxygen species. Active oxygen species includesuperoxides, peroxides in general, hydrogen peroxide, and hydroxylradical (OH). Other active species derived from active oxygens, such ashypochlorite ion (OCl—), hydroxyl free radicals on carbohydrates,“singlet oxygen”, or ozone, are also included. The active oxygen speciesdamage tissue directly. Moreover, they may cause indirect damage byattracting cells to the site of injury, or otherwise stimulating aninflammatory response.

A preferred antioxidant drug is superoxide dismutase (SOD). It isthought that SOD prevents tissue damage and inflammation by destroyingthe superoxide radical. Any of the forms of SOD are suitable. Sourcesinclude human, which is preferred for minimization of immunogenicity,and also other known sources including bovine and bacterial; SOD fromvarious tissues, such as liver, red cells, and others; SOD having anyfunctional metal ion, such as manganese, iron, copper, and zinc. Oneform (manganese) of recombinant human SOD is described in U.S. Pat. No.5,260,204 to Heckl et al, referencing EP-A 138111 to Chiron as a sourceof recombinant human copper/zinc SOD. Also included are SOD modifiedwith pendant polymers, such as polyethylene glycol or polyvinyl alcohol;natural SOD produced by recombinant or transgenic processes; and variantforms of SOD produced by mutation or protein engineering. All of theseprocesses are known in the art.

Alternative methods of delivery of SOD, or of other protein-based drugsof the antioxidant class, to the site include expression by transformedcells instilled at the site, and transient transformation of cells atthe site by recombinant DNA including a mammalian promoter, such as aplasmid, an expression cassette, or a viral vector. These may bedelivered locally by any suitable means, including liposomes, polymericcomposites, in solution via catheters and other similar devices, viaelectroporation or iontophoresis, and by other methods known in the art.

Other drugs having antioxidant activity (i.e., destroying or preventingformation of active oxygen) may be used in the prevention of adhesions,either in combination with SOD, in combination with each other, oralone. Protein drugs include catalases, peroxidases and general oxidasesor oxididative enzymes such as cytochrome P450, glutathione peroxidase,and other native or denatured hemoproteins. Most such molecules havedetectable peroxidase activity. Small-molecule drugs may act by directlyabsorbing or inactivating active oxygen species. These include vitamin C(ascorbic acid) and vitamin E (tocopherol), food-approved antioxidantssuch as BHT and BHA (butylated hydroxytoluene, butylatedhydroxyanisole), phenolic compounds and quinones, and highly hinderednitrogen free-radical scavangers such as 2,2,6,6-tetramethyl piperidine.Other drugs act by altering enzyme activity, and these may be veryeffective. Allopurinol, which inhibits the enzyme xanthine oxidase,substantially prevents the generation of superoxide, and has been foundto be highly effective. Other xanthine oxidase inhibitors are alsoexpected to be efficacious. Verapamil is known as a calcium-channelblocker, and is used as a vasodilator. It is highly effective inprevention of primary adhesions in the models described in the examples.Its mechanism of action is unknown, but it may prevent the stimulationof cells such as macrophages, which are believed to secrete activeoxygen when stimulated. As defined herein, verapamil is an inhibitor ofactive oxygen.

Not all materials effective in prevention of adhesion formulation actagainst active oxygen. Other materials such as fibrinolytics can beused, including urokinase, tissue plasminogen activator, and ancrod.These materials alone may be effective, for example, as described byDunn, et al., Am. J. Obstet. Gynecol. 164:1327-1330 (1991)), butenhanced when in combination with AOIs.

Formulations

The amount of AOI administered to the site will be adjusted to theparticular site, and to the nature of the controlled release means beingemployed. A suitable starting amount is a single dose; this may then beadjusted upwards or downwards to optimize the amount. The results shownin the Examples below indicate that a broad optimum or plateau existsfor SOD; many suitable AOIs, in other studies, also show broadeffectiveness regions. The prolonged presence of low levels of theinhibitor at the injured site, provides not only protection in theimmediate aftermath of surgery, but also minimizes damage andinflammation during at least the early stages of the healing process,and generally permits the use of lower effective doses.

The formulation of AOI and barrier materials should deliver AOI directlyto the injured tissue over a period of days from about 0.5 day up toabout 20 days under in vivo conditions. This is preferably controlled bythe gel incorporating the AOI, but may also be provided by a mechanicalbarrier such as a membrane or fabric. The formulation may also containadditional means for regulating the release of the inhibitor, such asmicrospheres, microcapsules, microparticles or liposomes (referred tojointly herein as “microspheres”), especially when the AOI is a smallmolecule of less than about 20,000 daltons, where the AOI is releasedfrom the microspheres into the gel, from which it diffuses into thetissue, alone or in combination with release of AOI from the gel. Othermeans for controlled release include intact or comminuted gels, polymerswith AOIs releasably bound thereto, and slowly dissolving particles ofthe AOIs or a complex thereof with an inert salt or organic moleculepratically. For example, verapamil as the free base is practicallyinsoluble in water, while its hydrochloride is very soluble.Encapsulation of the liquid free base form in conventional timed-releasemicrocapsules can be used to provide extended periods of delivery, byincorporating the microcapsules into the polymeric barrier.

The formulations may further contain excipients buffers, stabilizers,and other common additives, as known in the art of pharmaceuticalformulation. The formulations may also contain ingredients needed forthe formation of the barrier, such as polymerization-inducing orpolymerization-enabling materials. These may include photoinitiators,chain transfer reagents, and co-monomers.

The formulation may be prepared in more than one container, for mixingjust before use, and may be stabilized by lyophilization, freezing,dessication refrigeration, or other commonly used means. The formulationmust be sterile; where ingredients of the formulation are unstable,filter sterilization and aseptic filling are prefered.

Methods of Treatment

Application of Formulations to Tissues

The formulation can be applied to the affected tissues by any suitablemeans. These include spraying, washing with a medication-containingfluid, spreading with an instrument or by hand, and direct implantationof a preformed inhibitor-containing barrier. When the barrier is a gelor other solid form, the gel may be implanted; preferably, however, asolution of the mixture of gel precursor and inhibitor to be deliveredis delivered to the site of application, and gelled directly onto thetissue by an appropriate means. Preferred gelling means, because oftheir simplicity, are physical gelation due to a change in temperatureor to a cessation of shear; and photopolymerization of a photoreactivegelling monomer. Chemical redox reactions, ionic crosslinking, and othermethods of gel formation can also be utilized.

Instruments for performing delivery and gelling functions will beselected for the particular application, using principles andinstruments known in the art. These will typically include catheters orlaparoscopes for minimally invasive access to interior sites of thebody; syringes for surface or surgically exposed sites such as in tendonor wound repair; and appropriate light sources when a polymerizationreaction is required. Some suitable instruments are described in detailin U.S. Pat. Nos. 5,328,471, 5,213,580, and U.S. Ser. Nos. 08/054,385(WO 94/24962), 08/036,128 (WO 94/21324), and 08/265,448, which arehereby incorporated by reference.

Medical Indications

Treatment with the compositions, medications and methods describedherein is intended for any site in which adhesions form and havepotential or actual deleterious effects. These include primary, andespecially secondary, adhesions in the following: in the abdominalcavity, including intestine to intestine, and intestine to peritoneum;in the pelvic cavity, including adhesion of the uterus, ovaries orfallopian tubes to other structures including each other and the pelvicwall; in tendons and their support structures, including tendon topulley or to synovium; in the repair of nerve sheaths; in repair of thespinal column or disks; in the pericardium; in treatment of joints forinflammation and to prevent pannus formation; and in any situation inwhich adhesions form which impair function or cause pain.

Moreover, the compositions may be used in other conditions in which anunwanted tissue proliferation occurs. These can include restenosis ofarteries, repair of keloid or hypertrophic scars, hypertrophy whichobstructs ducts, such as benign prostatic hypertrophy, andendometriosis.

The present invention will be further understood by reference to thefollowing non-limiting examples. The following studies were designed to(1) demonstrate the potential for using locally delivered superoxidedismutase and (2) to compare the efficacy of hydrogel-delivered SOD withhydrogel alone or SOD alone in the prevention of postsurgical adhesions.

EXAMPLE 1 Release of Model Compounds

The compatability of SOD protein with the components of the FocalGelsystem was tested in vitro. The compatibility of SOD with each componentof the hydrogel system was tested step-wise, testing for any effect onSOD by gel electrophoresis, reversed phase HPLC, capillaryelectrophoresis and an enzymatic activity assay (cytochrome C). Sincephotopolymerization of the gel requires UV light, the effect of UVexposure (340-400 nm) on SOD stability was also evaluated.

Hydrogel Macromer (Pre-polymer) Preparation

In all pre-development studies, hydrogel was prepared in the same mannerusing the following method: Pluronic® F127 was added to a solution ofpotassium monobasic phosphate at pH 6.8. Photoinitiator (Irgacure® 651)was dissolved in tertiary butanol and added to the Pluronic®/buffersolution. Macromonomer and polyethylene glycol (PEG) 8000 were thenadded. Following sterile filtration, vials were filled and the water andt-butanol were removed by lyophilization. Prior to use in these studies,each vial of hydrogel was reconstituted with normal saline to arrive ata macromonomer/PEG 8000 concentration of 10% w/w, 3% w/w Pluronic®, and1200 ppm Irgacure® 651.

A. Formulation Compatibility Studies.

SOD compatibility in the hydrogel formulation was evaluated using astep-wise study design. SOD stability in each formulation component wastested in the presence and absence of ultraviolet light exposure (365nm). In these studies, protein stability was evaluated by gelelectrophoresis (SDS-PAGE and native PAGE), HPLC, capillaryelectrophoresis and enzymatic activity by cytochrome C reduction.

Control samples were prepared by diluting one vial of SOD (15,000 U, 5mg) with 1.5 mL PBS to give a final [SOD]=10 KU/mL. Additionally, 400 μLof this solution was diluted to 1 mL with PBS to give a final [SOD]=4KU/mL. Irgacure®/F127-treated samples were prepared by adding 1.5 mLIrgacure®/F127 (1200 ppm and 3% w/w, respectively) to 1 vial of SOD(final [SOD]=10 KU/mL). For all UV-treated samples, 300 μL of samplesolution was illuminated for either 20 or 60 seconds. Hydrogel-treatedsamples were prepared by adding 1.0 mL of hydrogel solution to a vial ofSOD to give a final [SOD]=15 KU/mL. 200 μL of this solution wasphotopolymerized for either 20 or 60 seconds after 1.5 mL of PBS wasadded to the hydrogel. Samples were placed in an incubator at 37° C. for24 hours prior to analysis.

Samples for electrophoresis were prepared by diluting 100 μL of samplewith 300 μL of sample buffer (Bio-Rad technical manual LIT-188 REV C).Samples were not heated prior to analysis. 10 μL of sample was loadedonto the gel except for samples where SOD was released from hydrogel (20μL used in these cases). Standards were run according to the vendor'sprotocol. Molecular weight bands in electrophoretic gels were integratedby image analysis.

There appears to be two low molecular weight subunit forms that are notidentical, with the bulk of the protein existing as a tetramericstructure. To give a baseline for relative compatibility comparisons,SDS-PAGE of SOD was initially performed using a saline (no exposure)control. The data suggest that 92% of the protein exists as the highmolecular weight form (67 kDa) with the remaining 8% existing as the lowmolecular weight monomer species (15.5 kDa). There was also a 12.7 kDapeak present, but the band intensity was very low and therefore notquantitated. Upon addition of the initiator and macromer formulationcomponents, the relative band intensities remained nearly constant, and,with the addition of UV exposure, no visible changes were observed.

Native-PAGE analysis of SOD control solutions (SOD in PBS pH 7.4,[SOD]=1.33 and 3.33 mg/mL) shows single band SOD migration with bandintensity directly related to protein content. Irgacure®/F127-treatmentand hydrogel-extraction solutions display similar SOD band migrationsand intensities as those displayed by the control.

SOD was incorporated into the initiator solution (3% F127 and 1200 ppmIrgacure®) by pipetting 2 mL of initiator solution into one vialcontaining SOD (final [SOD]=7.5 KU/mL). 300 μl aliquots of SOD/initiatorwere illuminated under the Black Ray lamp (power output=10 mW/cm2,lmax=365 nm). The results of analysis were analyzed as the total area ofthe SOD peaks, calculated SOD amount, expected SOD amount and percentrecovery. Irgacure® levels in control solutions were also determined andcompared to levels observed in the SOD/initiator samples.

SOD was also incorporated into hydrogel via bulk gel polymerizationusing 2 and 5 minute exposure times. Following polymerization, SOD wasextracted from 200 μL bulk gels (8 mm×10 mm) over two days in PBS. Eachof the extraction samples was analyzed for SOD amount and the cumulativeamount was calculated as the % recovered of initial. The peak area ofSOD in Irgacure®/F127 remained constant compared to the non-illuminatedcontrol after UV exposure (up to 5 min. exposure time). The data alsoshow that the degradation products of Irgacure® photoinitiator in thecontrol solutions were not altered in the SOD/Irgacure® treatmentsolutions. All degradation peaks observed in the samples were accountedfor by Irgacure® degradation. Extraction of SOD from hydrogel resultedin 86.4 and 78.2% of the expected level recovered. The extraction wasmost likely not complete because SOD has been shown to be only partiallyreleased over 49 hours in vitro. Chromatograms for SOD extracted fromHydrogel show that peak distributions remained similar to those incontrol solutions.

Capillary testing was performed. In this set of experiments, a standardcurve of SOD in water was prepared (1.48-11.84 KU/mL). SOD compatibilitysamples were prepared at 1.2, 1.6 and 11.9 KU/mL. Separation by CE showsthat three sharp peaks are present (3.15, 3.20 and 3.27 minutes). Thethird peak has a shoulder which is a possible fourth peak. Each peak wasintegrated separately and the third peak was integrated to include theshoulder peak area. The standard curve of total peak area versus SODconcentration shows excellent linearity (R{circumflex over ( )}2=1.000)over [SOD]=1.48 to 11.84 KU/mL. The results show that the detectedlevels of SOD in Irgacure®/F127 (no illumination) were 130 and 82% ofexpected levels. When SOD/initiator samples were illuminated, the SODlevels remained high regardless of SOD concentration. Results from low[SOD] samples (1.2 KU/mL) showed more response variability than thoseprepared at higher concentrations (11.9 KU/mL). SOD extracted from bulkphotopolymerized Hydrogel showed 89-108% of the expected SOD levelrecovered and the peak distribution remained similar to the SOD control.

Under standard assay conditions, cytochrome C (10⁻⁵ M) reduction wasmeasured at 25° C. with 5×10⁻⁵ M xanthine oxidase (XOD) in 50 mMpotassium phosphate buffer (pH 7.8) containing 0.1 mM EDTA. Inhibitionof the reduction of cytochrome C by 50% was defined as 1 unit of SODactivity. Continuous spectrophotometric rate determination was performedover 5 minutes at 550 nm using a Hitachi UV/Vis spectrophotometer.Compatibility solutions were prepared and treated at [SOD]=5000 U/mL,then diluted with normal saline to a final [SOD]=10 U/mL. Relativespecific activity was determined by comparing treatment solutionactivity to control solution activity ([control]=10 U/mL having 50%inhibition of cytochrome C reduction activity).

SOD in normal saline (10 U/mL, no illumination) was used as a controlsample for relative compatibility comparison. The theoretical enzymaticactivity as defined by the assay was 50% inhibition activity and thecontrol solution showed the expected response (51.5% inhibition). Uponthe addition of the initiator and/or macromer components, no dramaticchange in the SOD activity was observed. Additionally, when SOD/hydrogelformulations were exposed to 1 min. of UV exposure, SOD activity levels(50.9% inhibition) were retained.

In vitro Release Characteristics

Subsequently, bulk photopolymerized hydrogel devices containing fourlevels of SOD (1, 3, 5, and 10 KU/mL) were prepared and evaluated forSOD in vitro release kinetics. SOD was dissolved in each of theindividual components of the hydrogel prepolymer solution, in thepresence or absence of ultraviolet light (10 mW/cm²) and the SOD wasthen characterized by gel electrophoresis (SDS PAGE and native PAGE),reversed phase HPLC, capillary electrophoresis and enzymatic activityassay (as inhibition of cytochrome C reduction). No changes in proteincharacterization or enzymatic activity were observed using thesetechniques. The kinetics of release of SOD from bulk hydrogels weredetermined in vitro at hydrogel loads ranging from 1,000 to 10,000 U/mL.

10% macromer solutions were prepared using 1200 ppm Irgacure and 3% F127in normal saline. To parallel the in vivo study design, four doses ofSOD (1, 3, 5 and 10 KU/mL) were incorporated into the macromer solutionand bulk photopolymerized in 200 μL aliquots (365 nm, 10 mW/cm2). SODrelease in PBS was monitored over time using the micro-BCA method;activity of released SOD was also characterized using cytochrome Cinhibition analysis.

The hydrogel cross-link density and the effective size of the molecularspecies are two major determinants of the drug release kinetics out ofthe hydrogel. In this case, three molecular weight species of SOD (67kDa oligomer, 15.5 and 12.7 kDa monomers) are present. Based on datausing dextran model compounds, it was expected that the low molecularweight species would completely elute from the gel within the first 12hours and medium molecular weight species (67 kDa) would initially showa burst of release within the first 48 hours with prolonged releaseevident as the superficial diffusion zone is depleted.

The release of SOD from hydrogel in vitro in saline was biphasic.Hydrogels formed from 10% macromer solutions released 90% of theincorporated SOD within 48 hours (t_(1/2)=4 hours) with the remaining10% being released by zero-order kinetics over the following 7 days(t₁₀₀=8 days). In contrast to the data obtained with dextran, theincrease in the drug diffusion path length coupled with the hindereddiffusivity of the larger molecular weight species results in extendeddurations of release to 8 days. Specific activity analysis of sampleelution media demonstrates extended formulation stability.

EXAMPLE 2 Prevention of Primary Adhesions in Rat Model

Animal Models

In vivo efficacy experiments were performed in primary and secondary ratuterine horn adhesion models (RUHAM) to compare the relative efficaciesof SOD when delivered by IP bolus versus controlled hydrogel delivery.Control groups included untreated (injured) and hydrogel (no SOD)animals. The final in vivo efficacy studies used dose-range studydesigns (1, 3, 5 and 10 KU/mL) in primary and secondary RUHAM models.The endpoint used for in vivo evaluation studies was 1 weekpost-treatment.

Experiments were performed using two rat uterine horn models whichdevelop adhesions in response to an initial ischemic insult. The firstmodel generates de novo adhesions (primary model) over a 7 day timeperiod. The second model is a reformation (secondary) model whereby thefibrinous adhesions developed in the primary model are lysed andreformation of adhesions is observed 7 days after adhesiolysis. Fortysexually mature female Sprague-Dawley rats (225-250 grams) were used inthe primary adhesion model. The animals were anesthetized followingintramuscular injection of 4 mL/Kg of a mixture of ketamine (25 mg/mL),xylazine (1.3 mg/mL), and acepromazine (0.33 mg/mL). Aseptic techniquewas used throughout the surgical procedure. After preparing the abdomen,a 3 centimeter lower midline incision was made to expose the pelviccavity. The uterine horns were positioned to expose the vascular arcade.Ischemia to the central portion of the uterine horns was induced bycauterizing the vascular arcade using bipolar electrocautery. Care wastaken not to cauterize the most anterior and posterior vessels supplyingblood to the horn to maintain minimal blood flow and ensure organviability. Two additional injuries were made on the antimesentericsurface of the horn approximately 2.5 cm apart using electrocautery.Following surgical injury, animals were assigned to one of the fourtreatment groups in a random fashion. The musculoperitoneal layers andthe overlying fascia were closed with a 4-0 vicryl absorbable suture andthe skin incision closed using 7 mm stainless steel staples.

The animals were evaluated for adhesion formation at the end of oneweek. The “percent of adhesions” along the uterine horn is calculated asthe measured length of the uterine horns engaged in adhesions divided bythe entire length of the uterine horn multiplied by 100. The “percentefficacy” is 100 minus the “percent of adhesions.”

In a second experiment, seven days after initiation of the primaryadhesion model, animals (n=40) were opened and the uterine horns wereexposed once again. Using microscopic surgical technique, adhesionsbetween the uterine horns and other organs were carefully dissected andlysed. Bipolar electrocautery was used to maintain hemostasis. Uponcompletion of adhesiolysis, animals were assigned to different groups,treated according to protocol, and the peritoneal cavity was closed.Animals were evaluated at the end of a one week time period for adhesionreformation, and adhesion scores were calculated as described above.

In both the primary and secondary adhesion models, animals were assignedrandomly to one of four groups according to the following experimentaldesign:

Group 1: Control injury with no further treatment

Group 2: Hydrogel barrier alone

Group 3: SOD alone

Group 4: Hydrogel containing SOD

For treatment Groups 2 and 4 (where Hydrogel was required), formulationswere prepared as described above and 0.25 mLs of solution was appliedonto the medial and lateral surface of the uterine horns for a totalvolume of 1 mL per animal. The preparation was subsequentlyphotopolymerized by exposure to long wave ultraviolet light deliveringan nominal irradiance of 20 mW/cm² for 20 seconds.

In Group 3, lyophilized SOD reconstituted with normal saline was drippedonto the surface of each uterine horn in 0.25 mL aliquots as describedabove. Four experiments were conducted to determine the effect of doseon primary and secondary adhesion formation. Doses ranging from 2,000 to10,000 U/mL were compared when applied directly to peritoneal tissue andwhen added as a supplement to the Hydrogel formulation.

Results in Primary Adhesion Model.

The results are shown in FIG. 11. In all “untreated” control animals(Group 1), 93% or more of the uterine horn surface was adherent toadjacent mesometrium and/or organs resulting in efficacy scores of 7% orless. Hydrogel applied as a barrier to adhesion formation (Group 2)showed a broad range of efficacy values ranging from 11 to 46% efficacy.Application of SOD solution (Group 3) resulted in efficacy scores of86-93%. Efficacy scores ranged from 79 to 85% when hydrogel containingSOD was applied (Group 4). No significant effect on efficacy wasobserved whether the bolus dose of SOD or SOD incorporated intoHydrogel, respectively, was 2,000 (10000 U/kg) or 10,000 U/mL (50,000U/kg).

EXAMPLE 3 Prevention of Adhesion Reformation in Rat Model

Results in Secondary Adhesion Model.

The results are shown in FIG. 2. In all “untreated” control animals(Group 1), 94% or more of the uterine horn surface was adherent to theadjacent mesometrium or other organs resulting in efficacy scores of 6%or less. Hydrogel applied as a barrier to adhesion reformation (Group 2)resulted in efficacy scores of 20 to 40%. When SOD solution was applied(Group 3) scores ranged from 0 to 29%. Finally, application of SOD afterincorporation into Hydrogel (Group 4) resulted in efficacy scoresranging from 67 to 94%. No significant effect on efficacy was observedwhen a bolus dose of SOD or a dose of SOD incorporated into Hydrogel,respectively, was 2,000, 5,000, or 10,000 U/mL.

Since no significant difference was found as a function of dose, thedata from individual experiments were combined to summarize differencesbetween treatment groups for both primary and secondary models, as shownin FIG. 3.

Diamond, et al., Fert. and Ster. 47:864 (1987); Peters, et al., Br. J.Obstet. Gyn. 99:59 (1992); Lucian, et al., Obstet. & Gyn. 74:220 (1989);Luciano, et al., Fert. and Ster. 48:1025 (1987); and Surrey, et al., J.Repro. Med. 27:658 (1982), have demonstrated that reduction of secondaryadhesions is more difficult than primary adhesions in animal models.Based on the data presented here, it is likely that primary andsecondary adhesions in rats are formed through different pathologicsequences. When histologic evaluations and the propensity for adhesionformation at the wound sites are compared, the differences between thetwo models become apparent. Lysis of fibrin followed by adhesionresorption occurs from day 7 through 28 in the primary model. Incontrast, the secondary adhesion model results in persistent collagenousadhesions that do not resorb over an eight week period. These dataindicate that there is a need for a pharmacologic intervention thatlasts for a longer period of time to prevent secondary adhesions than asingle bolus can provide. Adhesions formed in this secondary model arequalitatively similar to those experienced in the clinical situation.Although other formulations of hydrogel have produced efficacy inadhesion models, the particular formulation and application method usedfor this study provided marginal efficacy as a barrier. However, SODloaded into the same formulation or the direct application of SODsolution to the uterine horns showed much higher efficacy in the primarymodel. This indicates that in this primary adhesion model, efficacy wasproduced by SOD due to early intervention in the pathologic sequencewhich is consistent with the production of oxygen-derived radicalsduring the initial stages of inflammation. Moreover, since the rate ofelimination of SOD from blood is rapid, one may speculate that theefficacy shown by the bolus dose occurred in a short time frame. In thesecondary model, there was a dramatic decline in efficacy when thebarrier alone or a bolus of SOD was applied. However, a significantlevel of efficacy was achieved when the two modes of therapy werecombined (i.e. the barrier loaded with SOD). This supports thehypothesis that more prolonged exposure to SOD is required when treatinglysed, mature collagenous adhesions similar to those formed in theclinical population, rather than the short-lived fibrinous adhesionsformed in the primary model.

Modifications and variations of the present invention will be obvious tothose skilled in the art from the foregoing detailed description. Suchmodifications and variations are intended to come within the scope ofthe appended claims.

We claim:
 1. A composition for the local alleviation of a medicalcondition caused by inflammation or unwanted tissue proliferation at asite, the composition comprising an effective amount of one or moreactive oxygen inhibitor compounds which destroy or prevent the formationof active oxygen species in a polymer solution or hydrogel, wherein thepolymer solution or hydrogel is administered to the site in a fluentform and forms a conforming barrier by ionic crosslinking, chemicalredox reaction, photopolymerization, or physical gelation at the site ofadministration, and wherein the barrier persists at the site for days toweeks.
 2. The composition of claim 1, where the banier is degradable invivo.
 3. The composilion of claim 1, where the polymer solution isphotopolymerizable.
 4. The composition of claim 1, where the polymersolution or hydrogel comprises 0.5% to 80% by weight of the composition.5. The composition of claim 4, where the polymer solution or hydrogelcomprises 2% to 50% by weight of the composition.
 6. The composition ofclaim 5, where the polymer solution or hydrogel comprises 4% to 30% byweight of the composition.
 7. The composition of claim 1, where theactive oxygen inhibitor compound is selected from the group consistingof superoxide dismutase, catalase, allopurinol, verapamil, andcombinations thereof.
 8. The composition of claim 7, where the inhibitorcompound is superoxide dismutase.
 9. The composition of claim 1 furthercomprising a biologically active compound other than an active oxygeninhibitor compound.
 10. A method for the prevention of localinflammation or tissue proliferation, comprising administering acomprising an effective amount of an active oxygen inhibitor compoundwhich destroys or prevents the formation of active oxygen species incombination with a polymer solution or hydrogel, wherein the polymersolution or hydrogel is administered to the site in a fluent form andforms a conforming barrierby ionic crosslinking, chemical redoxreaction, photopolymerization, or physical gelation at the site ofadministration, and wherein the barrier persists at the site for days toweeks.
 11. The method of claim 10, further comprising administering thecomposition in a pharmaceutically acceptable vehicle.
 12. The method ofclaim 10, where the proliferation to be inhibited is the formation of anadhesion.
 13. The method of claim 12, where the adhesion is a secondaryadhesion.
 14. The method of claim 10, where in the active oxygeninhibitor compound is selected from the group consisting of superoxidedismutase, catalase, allopurinol, verapamil, and combinations thereof.15. The method of claim 14, where the inhibitor compound is superoxidedismutese.
 16. The method of claim 10, wherein the active oxygeninhibitor compound is administered in a controlled release formulation.17. The method of claim 10, where the barrier-forming material is ahydrogel-forming polymer.
 18. The method of claim 10, further comprisingadministering at the site biologically active molecules that are notactive oxygen inhibitors.
 19. The method of claim 10, wherein thecontrolled release formulation is separate from the polymer solution orhydrogel forming the barrier.
 20. The composition of claim 1, where theproliferation to be inhibited is the formation of an adhesion.
 21. Thecomposition of claim 20, where the adhesion is a secondary adhesion. 22.The composition of claim 1, further comprising in the polymer solutionor hydrogel controlled drug delivery means for controlling the rate ofdelivery of the active oxygen inhibitor.